Digitimes has come into some rumors about Apple’s 2011 computer line-up. If the leaks are to be believed then the first half of 2011 will see “at least four upgraded MacBook Pros” and a new iMac panel size along with an iMac priced for mainstream buyers.

The new MacBook Pro revision is expected to have slight changes to the chassis and an upgrade to Apple’s Lion (OS X 10.7) operating system, which we can assumed would hit Apple’s other system’s at the same time. Currently Apple says Lion will be released in summer 2011, which works well with the rumor.

The report went on to note that Apple should ship more than 10 million computers in 2011 and will see a 30-40% growth in their notebook sales.

It’s nice to get some news–however slight–about what is in the pipeline from Apple, but this report doesn’t give buyers a whole lot to go on. With Intel’s Sandy Bridge arriving in January, the pressure will start to build for Apple to upgrade their computers, especially the high performance MacBook Pros. The current crop of MBPs is the “Mid-2010″ line so a change by mid-2011 seems to make sense, especially given the fact that a “Mid-2009″ model preceded the current one.

There is little doubt that we’ll see new graphics and processors hitting the new MacBook Pro line in 2011 the main question is when and which models/SKUs are affected. The 13-inch Pro should be the at the top of the list as it still runs Intel’s Core 2 Duo processor. As for timing, it won’t be in January with other manufacturer’s laptops so new Macs aren’t right around the bend.

The iMac is currently available in only two sizes (21.5-inch and 27-inches) so the addition of another size won’t come as a huge surprise, though it’s unlikely that Apple will introduce a smaller size. We’ll probably see a 24-inch or maybe even a 30-inch model while the 21.5-incher drops down to that “mainstream” price level, possibly featuring some less expensive (or just not upgraded) componentry.

The rumors are light, so I’m extrapolating here, but we will get a better idea as things get closer to the summer and we become better acquainted with Intel’s new line.